PROJECT SUMMARY According to the World Health Organization, about one third of the world?s population is infected with Mycobacterium tuberculosis (Mtb), and as many as 10% of infected individuals will develop active tuberculosis (TB) at some point after infection. TB is a curable disease, yet it still has a high mortality rate (in 2016, 1.7 million people died from the disease). The global control of TB is complicated due to the high incidence of TB in developing countries, and the emergence of drug resistant TB. Cfz is a drug that has been recently added to WHO recommended list of drugs to treat drug resistant TB strains, effectively able to shorten treatment times. However, oral administration of Cfz poses problems such as delayed onset and deleterious side effects (gastrointestinal, dermal, cardiac). An existing goal to improve TB treatment consists of developing effective aerosolized delivery of drugs, such as Cfz, to directly target the lungs. The development of improved drug therapeutics for treatment of diseases has been listed as a priority in the strategic plan of the National Institute of Allergy and Infectious Diseases (NIAID). Microparticle encapsulation has been studied for aerosol delivery of TB drugs. Critical parameters in the development of an efficient particle delivery system are: 1) deep lung delivery, 2) particle uptake by alveolar macrophages (the primary site of invasion and replication of Mtb) 3) drug release, 4) drug dosage, and 5) safety. Balancing the mass of drug delivered against release as well as ensuring efficient dispersal and safety is critical to an effective formulation. Microparticles with precise control over particle size for deep lung delivery and size-mediated phagocytosis can be prepared using spray drying. To address the limitations in drug release and dosage, Lynntech proposes to develop polymeric acetalated dextran (Ac-Dex) encapsulating Cfz. Differential drug release can be achieved through the use of pH- responsive Ac-Dex particles, able to release Cfz within the acidic environment in phagolysosomes, quickly increasing where the bulk of Mtb infection occurs. This release mechanism can quickly enable MIC of Cfz to be reached within macrophages, simultaneously increasing effectiveness while reducing the required dosage of Cfz, thus reducing side effects. Additionally, the by-products of Ac-Dex degradation (ethanol, acetone, dextran) are relatively benign. Our specific aims are devised to provide proof-of-concept on using and tuning these Ac- Dex particles for active Cfz release within Mtb infected cells. These aims include (1) developing novel Ac-Dex particles encapsulating Cfz, (2) demonstrate that particle uptake and release enhances in vitro Cfz delivery and bactericidal effect, and (3) evaluate uptake and release in pharmacokinetic (PK) and efficacy in vivo studies. The successful completion Phase I will demonstrate feasibility of developing Ac-Dex particles for inhaled delivery of Cfz. We will then incorporate optimal samples into dry powder formulations for aerosol delivery in a future Phase II effort. This research ultimately forms a platform for delivery of a variety of TB drugs and combinations thereof for TB treatment.